Messages in this thread | | | Date | Thu, 29 Jan 2015 16:22:05 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH 40/42] perf callchain: Save eh/debug frame offset for dwarf unwind |
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Em Thu, Jan 29, 2015 at 05:07:21PM +0900, Namhyung Kim escreveu: > When libunwind tries to resolve callchains it needs to know the offset > of .eh_frame_hdr or .debug_frame to access the dso. Since it calls > dso__data_fd(), it'll try to grab dso->lock everytime for same > information. So save it to dso_data struct and reuse it. > > Note that there's a window between dso__data_fd() and actual use of > the fd. The fd could be closed by other threads to deal with the open > file limit in dso cache code. But I think it's ok since in that case > elf_section_offset() will return 0 so it'll be tried in next acess.
Thanks, applied after rewriting the changelog to read as:
--- perf callchain: Cache eh/debug frame offset for dwarf unwind When libunwind tries to resolve callchains it needs to know the offset of .eh_frame_hdr or .debug_frame to access the dso. Since it will always return the same result for a given DSO, just cache the result as an optimization. ---
- Arnaldo
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